We'll assume you've been to Twitter.com and know it's a list of short postings, limited to 140 characters. You probably know you can follow people and their posts show up in your time line.

But what's it good for? At it's most basic, it's good for keeping in touch. Twitter can be delivered in several ways: on the Web, in a separate application, or by text message. Here's how to do the text thing.

In settings, tell Twitter what your phone number is and activate your number. From then on, when send your text message to 40404, Twitter knows by your phone number it's you and posts the message to your account.

You can also have other people's updates texted to you. Send "on" to 40404 to get them from everyone you follow, and "off" to stop them. You can shut off individuals in their twitter profiles on the Web by visiting an individual's Twitter profile. If you pay for text messages, you need to be careful with using Twitter over text. I prefer to use an application on my phone. It saves on text-messaging costs and allows me to have a more visual interface.

Great! Now you have lots of posts. What the heck are these people writing? RT @acedtect OH: blah blah blah. Let's start with the @ symbol. You know it well from e-mail. It's common practice to refer to people by their Twitter names with the @ symbol in front. This makes their name into a link. So it's used as a reply:

Or just to talk about them:

The excellent thing about the @ sign is it lets you send a message to someone even if they don't follow you. Take someone outstandingly popular, like Jason Howell. He can't possibly follow everyone who follows him. But folks can message him by using his handle @raygun01 in their message. When he clicks on the replies tab in his Twitter account, he sees all the folks who messaged him.

Remember, your @ replies can potentially be seen by anyone. If you need a reply that's a little more private, try the direct message. You can either type d and then the username like this:

Or you can go into the Direct Message section of the site. Either way, the messages are not public. Do keep in mind, you can only send a direct message to someone who follows you.

Abbreviations

Let's get into some shorthand. You may also run across something like this:

You might first read that and think it reads, "OH! That man is a pig..." But the OH stands for overheard. When you want to anonymously pass along something someone else said, say in a restaurant, or even on a TV show, you type OH and then the overheard phrase in quotes.

Another common oddity is RT. As in:

The RT stands for ReTweet. You're passing along to your friends, something someone else said because you find it informative or funny or whatever. At the same time, you're giving credit to the original poster.

And before we move on from the posts themselves, a little about hash tags. They have nothing to do with potatoes OR marijuana. Unless you want them to. It refers to putting the pound sign in front of a word. This "tags" your posting. So, let's say you're attending the Consumer Electronics Show. Every post you make about the show could end #CES. This would make it easier for folks looking for information about the show to find it.

What makes a good Twitter post?

Finally, what should you write? Literally answering "What are you doing?" may get boring fast. At least to folks following your time line. Some of the most enjoyable posts are witty observations, breaking news, and links to interesting stuff, like Web sites and pictures. In fact, many mobile phone applications allow you to take a picture and automatically add it to your posting. If you want to do that, you need to get to know TwitPic.

There's a whole heck of a lot more to cover, but now you know the basics. In fact, now you can just ask other Twitterers what some of their other favorite tricks and tips are and I'm sure they'll @ you right back. Have fun getting started with Twitter.